Head suspension assemblies are spring structures in disk drives that position a head assembly in read/write relationship to the surface of a rapidly spinning disk or similar data storage device. The head suspension assembly presses the head toward the disk surface with a precise force applied in a predetermined location. The head assembly "flies" over the disk surface at a height established by equilibrium between the downward force of the head suspension assembly and the lift force of the air stream generated by the spinning disk.
A head suspension assembly (HSA) includes the head suspension assembly, the head assembly, and an interconnect assembly. The interconnect assembly includes transmission elements to transmit data to and from the head assembly. HSA's are used in magnetic hard disk drives, the most common type today, or other types of drives such as optical disk drives.
The head suspension assembly includes two spring structures, a load beam and a gimbal, each a balanced combination of rigid regions and flexible spring regions. The load beam is a resilient member designed to provide lateral stiffness and to apply the necessary load on the head assembly. The gimbal is a spring at the distal end of the head suspension assembly and of the load beam. The purpose of the gimbal is to hold the head assembly at an appropriate orientation and at a constant distance over the disk, even as the load beam flexes and twists. The head assembly is attached to the gimbal and includes a read/write transducer or head attached to an air bearing head slider. The head assembly also includes electrical terminals for interconnection to the interconnect assembly for receiving and relaying read and write signals.
The head suspension assembly is attached at its proximal end either directly or by means of a rigid arm to a linear or rotary motion actuator. The actuator rapidly moves (and then abruptly stops) the HSA, positioning the head assembly over any position on the disk. The closer the head assembly can fly to the surface of the magnetic disk, the more densely information can be stored on the d:Lsk. However, the head assembly must not touch the disk ("crash"), since impact with the spinning disk can potentially destroy the head, the surface of the disk, and the stored data.
Amplifying and control electronic circuits process, send, and receive the data signals to and from the head assembly. Traditional head assemblies complete a read/write circuit loop with two conductors, usually copper wires encapsulated in a plastic sheath. Newer magneto-resistance head assemblies require four or more independent conductors. The interconnect assembly includes the conductors and accompanying insulators and connectors.
Traditional hand mounting and placement of electrical conductors and their connections between the interconnect assembly and the read/write head slider is imprecise and costly. Accurate placement of electrical conductors and their connections is especially critical in the delicate gimbal region. As the industry transitions to smaller head slider/transducer sizes to increase data storage density, limitations of the current electrical interconnecting technology increase the potential for read/write errors and impose ceilings on data storage density.
Using present interconnect technology, two to five lengths of wire are hand bonded to the head assembly. The lengths of wire are typically shaped by hand to form a service loop between the head assembly and the head suspension assembly and to position the wire along a predetermined wire path on the head suspension assembly. Precise formation of the service loop is required. Too tight of a service loop places an unwanted torque on the head slider and can cause flying attitude errors. Too loose of a service loop might allow the wire to interfere with the spinning disk. Moreover, throughout the process of handling the head slider and wires there is a risk of damaging the wires or the delicate load beam and gimbal.